Intermediates of duocarmycin SA, which is expected to be used as an anticancer agent, and derivatives thereof, and production of these compounds have been disclosed, for example, in J. Antibiotics 43, 1037 (1990), ibid. 44, 1045 (1991), Japanese Patent Laid-open Pub. No. Hei 2-177890, Japanese Patent Laid-open Pub. No. Hei 5-208979, Japanese Patent Laid-open Pub. No. Hei 7-53558, J. Am. Chem. Soc. 114, 10056 (1992), Tetrahedron Lett. 35, 2573 (1994), and Chem. Pharm. Bull. 43, 1064 (1995).
Among these known methods for producing duocarmycin SA and its derivatives, the method by formentation allows only a low productivity, and the chemical synthesis needs many steps for producing an optically active one or accompanies arduous optical resolution of an intermediate. Thus, it was difficult to efficiently produce optically active duocarmycin SA.
The object of the present invention is to provide intermediates for efficiently producing duocarmycin SA, which is expected to be used as an anticancer agent, and its derivatives, and methods for producing the same.